Electric mercury tube switch



Oct. 22, .1935.

|. E MccABE v ELECTRIC MERCURY TUBE SWITCH Filed Dec. s1', 1.928

2 Sheets-Sheet l- ATTORNEY ot,2z,193s. l. E. MCCABE 2,018,310

ELECTRIC MERCURY TUBE SWITCH Filed Dec. 31, 19.28 2 Sheets- Sheet 2INVENTOR A. E. lll'c C1936'.

- Byw mfr- ATTORNEY Patented Oct. 22, 1935 UNITED STATES PATENT OFFICEELECTRIC MERCURY TUBE SWITCH 1m E. McCabe, Chicago. nl. e ApplicationDecember 31, 1928, Serial No. 329,548 2` Claims. (C1. zoo-152) Thisinvention relates to the manufacture of electric mercury tube switches,and more particularly to mercury tube switches with both electrodesprojecting from one end.

It is an object of this invention to manufactureJ mercury tube switchesby machinery in a Way that will not only lessen the number of operationsit has heretofore necessitated by hand,

' but also increase the uniformity of the product. It is anotherobject'of this invention to provide a construction of switch tube inwhich a blown bulb may be employed in place of shaping a piece of glassytubing for this ypurpose. Bulbs blown in a mold are much more uniformthan heating and closing one end of a tube by hand. It is also an objectof this invention to provide a filling stem in the sealed end of thebulb that also supports theleading in wires of the electrodes andprovide means in vconnection with the exterior projection of theflllinglstem for supporting and reinforcing the connections of the lead wiresto the electrodes and the exterior lines.

With these and other objects in view, reference is made to theaccompanying sheets of drawings which illustrate -preferred forms ofthis invention; it being understood that minor detail departure may bemade therefrom without departing from the scope of this invention.

lfn the drawings:

'port holding the leading in wires attached to their respectiveelectrodes and the filling stem,

before the bulb is heated and the heated portion pinched to embrace thesame.

'Figure 2 is a similar view of the bulb, leading in wires carrying theelectrodes, and the filling4 l stem,A afterthe open end of the bulb hasbeen heated and the side walls pressed together to form an end seal,engaging and supporting the wires and tube. 'i

Figure 3 is a view similar to Figure 2, illustrating the filling stemtipped and sealed off.

Figure 4 is. a view similar to Figure 3 showing the leading in wiresconnected to the lead wires l Q/r exterior line and one means forsupporting and reinforcing these connections.

-Figure 1 is a view^in central horizontal sec-1 tion of the switch bulbsupported above the sup-v Figure 9 is a view similar to Figure 7illustrat#l ing another type of -switch connection. i

Figure 10 is a view7 in side elevation of Figure 9.

Figure 11 isa top plan view of Figure 6.

Mercury tube switches of various types have 5 long been used in electriccircuits for various purposes. Of late years they have been extensivelyused in control devices such as employed in domesticrefrigeratingmachines, electric flashing signs, domestic oil burner systems and thelike. 10 Such mercury tube switches usually comprise an elongatedcylindrical glass container closed` at both ends, into which theelectrodes of the circuit to be controlled project, usually adjacent toeachother and either through a side wall ad- 15 jacent a closed end orthrough a closed end, the

air exhausted from the container and a, body of nercury and an inert gasinserted, thel body of e mercury being sufficient when the container ortube is tilted toward one end, the mercury ilow- 20 ing to-that en'dcloses the circuit between the electrodes, and when tilted in theopposite direction, the mercury flows away from the electrodesV andopens the circuit therebetween. 'I'he containers were usually formed'from sections of glass 25 A tubing heated and closed by hand, and more`recently the electrodes have'been supported ina machine, an open end ofthe same tube supported over the electrode, heated and the sides pressedtogether to close that end and seal the electrodes 30 therein at thesame time, while the other end has been manipulated by hand 'to be rstdrawn toa small tube through which the air could be exhausted and themercury and inert gas inserted, then the tube was tipped and sealed oifto close 35 that end. v

The present invention contemplates the employment of bulbs blown in amold having cylindrical sides and a right angular closed end, such v asthe bulb illustrated in Figure 1. which 1n'sures 4,0

uniform dimensions. The electrodes (2) are each formed of a metal thatwill not amalgamatewith f the mercury within the tube when the circuitis made and brokethereby, and are preferably vwelded to leadingrin wires.(3) which are of such 45 a character aswill form a seal with the wallsof the tube, which is usual construction. The bulb (i) is` graspedin'movable jaws (id) and the leading in wires .1(3) are positioned inproper relation in ay stationary .block (lb) of la. machine 50 whichincludes :means for heating the walls of `the bulb about the open enduntilplastic, and le the walls ofthe bulb are plastic, pinc em; togetherabout the leading in wires, forming ai at projecting end closure (l) asshown in rieures 2\nd 4, au er' which machinery ie of 'knownconstructibmin the glass manipulating art.

This invention contemplates furtherl the pro-- vision of a filling stem(5) in the form of a small.

glass tube and means for supportingthe. same in the block (Ib) in linewith and intermediate the leading in wires (3) with its end projecting asuillcient distance -above the surface of thefizlock to communicate withthe interiorof the bulb (I) after the plasticV open end has been closedabout same to shape the bulb properly after pressing,V

or air may be blown through the hole made by the solid wire after sameis removed. The manner in which this is accomplished is disclosed inLetters Patent. No. 1,872,070, granted Ira .E. McCabe andlKarl HuncikerAugust 16, 1932 and in the application of Karl Hunciker, Serial, No.393,389,'allowed July 21, 1932 and assigned to Ira E. McCabe.` Theclosed bulb is then removed from the machine as shown in FigureZ, andthe air removed from the interior and the desired amount of mercury andthe desired inert gas admitted through the illling stem (5) and the stemtipped and sealed of! adjacent the body.of I the seal (I) leaving aprojecting tip ('I).

Lead wires (8) preferably formed of ne tubular beaded wires having theusual insulation, are

then ford over each extending leading in wire (l), as shown in Figure 4,a band or flat ring of insulating material (8') is then,slld down overthe lead wires (l) until it engages the end of the 'glass seal, whichband or ring snugly ilts over and holds together the joints of theleadwires (t) 'with the leading in wires (3) forming ajoint in accordancewith tle prior patent No. 1,640,869,

granted-R. W. Armstrong -and Ira E. McCabe August30, 1927, although anyother usual formingconnection may be employed. Another band or flat ring(I) of insulatingfmaterial is then snugly placed about the outside of--the ends lof the covered' joints of the lead wires which in` sulationalso embraces the exterior of the end4 closure (I).` It isf-to benotedthat the leading inwires (I) and tip (1) of the filling stem arepositioned in .such relation that the insulated fends of the lead wires(I) bear against the tip' '(1), and when the surrounding band (0) is-inl place, the joints are supported and reinforced sothat ,pulls or tugson the lead wires (I) .out

QLline'with the leading in wir,(3);'arereaisted by the band (s),preventing injury'te these joints so surrounded.

while thererm iure 'deeiibed is a' preferredform of supporting andreinforcing the lead and- -leading in wire joints, the same may beaccom` plished in otherways to bind. the joints tothe rigid projectingtip (1) without departing from the scope of this invention. Other formsfor accomplishing the result contemplated are illusrated in Figures 6 to-11, inclusive.

' In Figure Bithe leadwires (I) extendin prolongation of the wires ,3.In Figure 'I the lead wires (I) are bent parallel to eachother and at.right angles to the -plane through the -ing movement or strain 'to thewires 3. In Figure 9 the leadwires (l) are bent. away. from each ,otherin the piane through the wires l.

While the insulating tubular band l makes a satisfactory binding andreinforcing support it 6 I would be dimeult te apply'te the types shownin Figures 'I-fy and 8. Since this invention contemplates means forsupporting and reinforcing the 'switch connections, a non-conductingplastic substance Il may be worked about and between l0 `the joints oftheJead wires, lling stem and sealed end of the tube- I, which willafterwards harden and support and reinforce the joints. Sealing wax,bakelite, or any non-conducting Vcementitious material may be employedfor thislii' purpose, and should not only surround the lead wire jointsand tipped end of the illling stem but should also embrace the sealedend of `the tube and `completely'cover the tip ofthe liing tube, asshown Figures 8', 10 and 11.

Before draw one end of a tubeto form a villing stem, even after theelectrodes were sealed in .one end,

*as shown herein. 'I'hen after the air had -been 25 structure' whichprotects the tip of the nlling 35 l stemandby surrounding and engagingboth the leadwires and tipof the illling stem L:a much moredurablermercury tube switch is produced..

-WhatI claimis:

1. An electric mercury tube switch including 40 a cylindrical containerhaving a tipless closure -.at one .end andi..having projectingelectrodes and an interposed filling stem sealed inthe other end withiiexiblelead wires attached t0 the Projecting electrodes on each side ofthe nlling' stem, and

means seclning the electrodeswith the attached flexible lead wires totherigid nlling stem, whereby the lead wires may be flexed .withutimpart- Projecting elec- 2. An electric mercury tube switch including .acylindrical` container having a tipless closure at one end and\having aprojecting filling stem with electrodes projecting on each side thereofsealed in the other end withflexible lead wires. surrounding andattached to the projecting elec'- trodes throughout the externalportions thereofand filling in the space between the electrodes andstem, the end of the filling stem tipp'edin.-

line with 'the exterior "termiriations of the/ere` t0 spectiveelectrodes, and a band of protective material surrounding' theelectrodes witlrthe attached flexible leads, interposed rigid nilingstem and-end of the tube seal to bind the attached portions of the`flexible leads to the electrodes and to the rigid lling stem, to coverand to protect the attaching means and to impart rigidity to the partsprojecting from the seale'dend of 'y Y .msnMccABE mA the tube.

e blown bulbs I were employed iii switches of this character; it wascustomary to

